gfs2: Call unlock_new_inode before d_instantiate

As Neil Brown describes in detail in the link referenced below, new
inodes must be unlocked before they can be instantiated.

An even better fix is to use d_instantiate_new(), which combines
d_instantiate() and unlock_new_inode().

Fixes: 3d36e57 ("gfs2: gfs2_create_inode rework")
Reported-by: syzbot+0ea5108a1f5fb4fcc2d8@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-fsdevel/177153754005.8396.8777398743501764194@noble.neil.brown.name/
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Author: Andreas Gruenbacher

fs/gfs2/inode.c

@@ -892,7 +892,7 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 		goto fail_gunlock4;
 
 	mark_inode_dirty(inode);
-	d_instantiate(dentry, inode);
+	d_instantiate_new(dentry, inode);
 	/* After instantiate, errors should result in evict which will destroy
 	 * both inode and iopen glocks properly. */
 	if (file) {
@@ -904,7 +904,6 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 	gfs2_glock_dq_uninit(&gh);
 	gfs2_glock_put(io_gl);
 	gfs2_qa_put(dip);
-	unlock_new_inode(inode);
 	return error;
 
 fail_gunlock4: